Organometallic compositons

ABSTRACT

A composition suitable for use as a catalyst for the reaction of an isocyanate compound or prepolymer thereof with an alcohol to form a polyurethane comprises a mixture of (a)an organometallic compound selected from: (i) a compound of formula M(RO) 4 , where M is titanium, zirconium, hafnium, aluminium, cobalt or iron or a mixture of these metals and OR is the residue of an alcohol ROH in which R comprises an (optionally substituted) C 1-30  cyclic, branched or linear, alkyl, alkenyl, aryl or alkyl-aryl group or a mixture thereof, or; (ii) a complex of titanium, zirconium and/or hafnium and an acetoacetate ester and (b) a coordinating compound selected from a ketone, aldhehyde, carboxylic acid, sulphonic acid, nitride or an imine. An isocyanate composition containing a catalyst of the claimed composition is also described.

[0001] This invention relates to organometallic compositions which areuseful in catalysing the reaction between a polyisocyanate and acomposition reactive therewith, such as a polyol, to form polyurethaneor like compositions.

[0002] The reaction between isocyanates and polyisocyanates with apolyol or other hydroxyl-bearing component is used in many applicationsin which it is necessary to effect curing of polyurethane compositions,e.g. in polyurethane coatings, adhesives, mouldings, sealants, rigid orflexible foam manufacture, elastomers or when organic polyisocyanatesare used as binders for lignocellulosic material in the manufacture ofsheets or moulded bodies such as waferboard, chipboard, fibreboard andplywood etc.

[0003] Catalysts for polyurethane manufacture are conventionally basedon tin compounds such as dibutyl tin dilaurate or compositions ofmercury such as phenyl mercuric neodecanoate. More recently, compoundsbased upon metals such as titanium or nickel have been used.

[0004] A polyisocyanate composition is disclosed in PCT Application WO97/17388 which comprises a Group IVB metal compound, preferably atitanium chelate, optionally in combination with a compatibilisingcompound and/or conventional release agents. Although these compositionsperform well as binders for lignocellulosic material and provide goodrelease performance, it is desirable to develop a more economicalcomposition which provides improved stability on storage before use,together with good curing properties and excellent bonding strength whenapplied to the lignocellulosic material.

[0005] U.S. Pat. No. 5,846,897 discloses zirconium compounds withdiketones or alkylacetoacetates which catalyse the isocyanate—alcoholreaction having the chemical structure: Me (X1, X2, X3, X4) wherein Meis zirconium (Zr) or hafnium (Hf) and X1, X2, X3, and X4, are the sameor different and selected from the group consisting of a diketone and analkylacetoacetate having the structures: R₁COCH₂COR₂ and R₁OCOCH₂COR₂wherein each of R₁ and R₂ is a branched or linear C1-C20 hydrocarbon andat least one of X1, X2, X3, and X4 is a diketone with structure (II)wherein the total number of carbons in R₁+R₂ is at least 4.

[0006] International Patent Application WO 00/02855 discloses thatcertain compounds of Group IVB metals can be used to cure isocyanate andpolyisocyanate compositions and these compositions are very stable onprolonged storage and economical when used for binding lignocellulosicmaterial. The compounds disclosed are complexes of titanium, zirconiumand/or hafnium and a acetoacetate ester in which the molar ratio of Tior Hf to acetoacetate ester is in the range 1:2.5 to 1:10 or the molarratio of Zr to acetoacetate ester is in the range 1:4.5 to 1:10 and saidacetoacetate ester is an ester of an alcohol containing 1 to 6 carbonatoms.

[0007] It is desirable to be able to control the rate of the reaction ofthe isocyanate in order to improve the properties of the resultingpolyurethane. It may also be desirable to retard the reaction in orderthat curing may be effected at a precise time, for example to enable theisocyanate composition or a prepolymer to be thoroughly mixed andapplied, e.g. to a mould or a surface before the curing reaction begins.The time between mixing the isocyanate composition and other componentsof the polymer system and the increase in viscosity which tends toinhibit mixing and pouring etc is commonly referred to as the “creamtime” of the mixture. It is beneficial to provide a polyisocyanatesystem which has a cream time which is long enough to allow forsufficient handling and manipulation of the mixed polymer precursor butwhich polymerises rapidly when required. It is also beneficial toprovide a polyisocyanate system which may be rapidly polymerised whencertain conditions, for example a particular temperature, is applied.

[0008] Furthermore it is desirable to be able to mix the catalyst systeminto one of the components (i.e. polyisocyanate or polyol) used to formthe polyurethane system and then to be able to store the mixture for aperiod of up to several weeks without significant change in the curingcharacteristics of the mixture, i.e. to provide a curable component of apolyurethane system which has an acceptable shelf-life.

[0009] GB-A-2303372 discloses a process for manufacturing polyurethanes,especially foams, using a catalyst system comprising at least one metalacetyl acetonate and acetyl acetone. The acetyl acetone provides a delaymechanism by inhibiting the catalytic activity of the metal acetylacetonate until the acetyl acetone is driven off by heating the mixtureto above the boiling point of the acetyl acetone.

[0010] It is an object of the present invention to provide an improvedorganometallic composition which is useful in the curing ofpolyisocyanate compositions.

[0011] According to the invention, a composition suitable for use as acatalyst for the reaction of an isocyanate compound or prepolymerthereof with an alcohol or polyol to form a polyurethane comprises amixture of

[0012] (a)an organometallic compound selected from

[0013] (i) an alkoxide compound of formula M(OR)_(x), where M istitanium, zirconium, hafnium aluminium, cobalt or iron or a mixture ofthese metals, where x is the valency of the metal, and OR is the residueof an alcohol ROH in which R comprises an (optionally substituted) C₁₋₃₀cyclic, branched or linear, alkyl, alkenyl, aryl or alkyl-aryl group ora mixture thereof, or

[0014] (ii) a complex of titanium, zirconium and/or hafnium and anacetoacetate ester and

[0015] (b) a coordinating compound selected from a ketone, aldehyde,carboxylic acid, sulphonic acid, nitrile or an imine, wherein saidcoordinating compound does not comprise a diketone or an acetoacetateester.

[0016] In a further aspect of the invention we provide a curablecomposition for the manufacture of a polyurethane material saidcomposition comprising.

[0017] A. a polyol component and

[0018] B. a polyisocyanate component and

[0019] C. a catalyst composition comprising a mixture of:

[0020] (a)an organometallic compound selected from

[0021] (i) an alkoxide compound of formula M(OR)_(x), where M istitanium, zirconium, hafnium aluminium, cobalt or iron or a mixture ofthese metals, where x is the valency of the metal, and OR is the residueof an alcohol ROH in which R comprises an (optonally substituted) C₁₋₃₀cyclic, branched or linear, alkyl, alkenyl, aryl or alkyl-aryl group ora mixture thereof, or

[0022] (ii) a complex of titanium, zirconium and/or hafnium and, anacetoacetate ester and

[0023] (b) a coordinating compound selected from a ketone, aldehyde,carboxylic acid, sulphonic acid, nitrile or an imine, wherein saidcoordinatng compound does not comprise a diketone or an acetoacetateester.

[0024] In a further aspect of the invention we provide a process for themanufacture of a polyurethane composition, comprising the step of mixingtogether a a polyol component and a polyisocyanate component and acatalyst composition, said catalyst composition comprising a mixture of

[0025] ((a)an organometallic compound selected from

[0026] (i) an alkoxide compound of formula M(OR)_(x), where M istitanium, zirconium, hafnium aluminium, cobalt or iron or a mixture ofthese metals, where x is the valency of the metal, and OR is the residueof an alcohol ROH in which R comprises an (optionally substituted) C₁₋₃₀cyclic, branched or linear, alkyl, alkenyl, aryl or alkyl-aryl group ora mixture thereof, or

[0027] (ii) a complex of titanium, zirconium and/or hafnium and anacetoacetate ester and

[0028] (b) a coordinating compound selected from a ketone, aldehyde,carboxylic acid, sulphonic acid, nitrile or an imine, wherein saidcoordinating compound does not comprise a diketone or an acetoacetateester.

[0029] The catalyst composition may be mixed with either the polyol orthe-polyisocyanate components or added to a mixture of the saidcomponents or to a prepolymer having both polyol and isocyanatefunctionality.

[0030] The mixture may be held at an elevated temperature in order toeffect curing. It is a particular benefit of the present catalyst andprocess that the polymerisation reaction may be delayed at lowertemperatures and initiated at higher temperatures so that thepolymerisation may be controlled by controlling the temperature of thereaction medium. For example, the polymerisation may take place at fromroom temperature to 200° C., more preferably at temperatures up to about150° C. The temperature used depends upon the catalyst and the nature ofthe polyurethane reaction mixture used. It is particularly beneficial toprovide such a catalyst so that the polyurethane reaction mixture isflowable and may be manipulated at low temperatures and then caused tocure by raising the temperature. Such a system enables e.g. an adhesivemade from the polyurethane mixture to be repositioned at lowtemperatures or for a polyurethane mixture to be filled into a mouldbefore the mixture begins to polymerise.

[0031] The catalyst may be added neat or in a solvent such as toluenefor example.

[0032] M is selected from the group consisting titanium, zirconium,hafnium, aluminium, cobalt or iron or a mixture of these metals but in apreferred form M is Ti, Al or Zr, especially Ti.

[0033] The group RO is an alkoxide group in which R is a substituted orunsubstituted, C₁₋₃₀ cyclic, branched or linear, alkyl, alkenyl, aryl oralkyl-aryl group or a mixture thereof In some applications, R preferablycontains up to 6 carbon atoms and, more preferably, up to 4 carbonatoms. Generally, all four OR groups will be identical but alkoxidesderived from a mixture of alcohols can be used and mixtures of alkoxidescan be employed when more than one metal is present in the complex. Insuitable compositions, R is ethyl, iso-propyl, n-propyl, t-butyl orn-butyl, 2-ethyl hexyl or other branched octyl species such asiso-octyl. (2,4,4 trimethyl 1 pentanol) or mixed isomers of branchedalkyl alcohol species such as the “Exxal™” products, e.g. Exxal 8,available from Exxon. Other alcohols are also suitable for forming thealkoxide.

[0034] Suitable alkoxides include tetramethoxytitanium,tetra-ethoxytitanium, tetra-isopropoxytanium, tetra-n-propoxytitanium,tetrabutoxytitanium, tetrapropoxyzirconium, tetrabutoxyzirconium,tetra-n-propoxyhafnium and tetra-n-butoxyhafnium. Alkoxides of higheralcohols may be prepared by transesterification of a lower alkoxide asis known in the art.

[0035] The coordinating compound is selected from a ketone, an aldehyde(such as an alkyl or aryl aldehyde), a carboxylic acid (such asaliphatic carboxylic acids e.g. stearic acid), a sulphonic acid (analkyl or aryl sulphonic acid which is preferably substituted, e.g.4-dodecylbenzenesulphonic acid or p-toluene sulphonic acid), a nitrile(e.g. valeronitrile or acetonitrile) or an imine (such as for examplethe reaction product of an alkyl or aryl aldehyde with aniline). Thecoordinating compound preferably does not comprise a diketone or anacetoacetate ester.

[0036] Preferred compounds include ketones, for example alkyl ketones,especially simple mono-ketones such as methyl ethyl ketone or aromaticketones. We have found that certain properties such as shelf-life may beenhanced if the keto-enol tautomerisation equilibrium of the ketonefavours the ketone form under the conditions used to make and store thecompositions, i.e. there is a very significant excess of the keto form.To this end, certain ketones in which the enol form is made only slowlyor with difficulty may be preferred in certain circumstances. Suchketones include those where the C atom which is adjacent the carbonylgroup (the α-C atom) is substituted as in 2,4 dimethyl petan-3one, forexample. The substituent may be an alkyl or aryl group.

[0037] The molar ratio of organometallic compound to coordinatingcompound in the composition is preferably in the range 1:0.5 (morepreferably 1:1) to 1:10. When the metal is titanium, the molar ratio ispreferably in the range 1:0.5 to 1:4 and more preferably in the range1:1 to 1:3, especially about 1:2.5. When the metal is hafnium orzirconium, the molar ratio is preferably 1:4 to 1:10 and more preferably1:4 to 1:8, hafnium or zirconium to total coordinating compound.

[0038] The compositions may be made by mixing together theorganometallic compound and the coordinating compound until ahomogeneous mixture is formed. Preferably the mixing is carried outunder an inert atmosphere such as nitrogen because the compositions maybe moisture sensitive.

[0039] The catalyst compositions of the invention are particularlyuseful as curing agents in polyurethane systems. Polyurethane systemstypically comprise a polyisocyanate component and a polyol component ora prepolymer which comprises the polyol and isocyanate components. Thepolyurethane system may comprise more than one type of polyol orpolyisocyanate compound.

[0040] The isocyanate compositions suitable for use with the catalystsof the present invention may be any organic polyisocyanate compound ormixture of organic polyisocyanate compounds, provided said compoundshave at least 2 isocyanate groups. Organic polyisocyanates includediisocyanates, particularly aromatic diisocyanates, and isocyanates ofhigher functionality.

[0041] Examples of organic polyisocyanates include aliphatic isocyanatessuch as hexamethylene diisocyanate and isophorone diisocyanate; andaromatic isocyanates such as m- and p-phenylene diisocyanate,tolylene-2,4- and tolylene-2,6-diisocyanate,diphenylmethane-4,4′-diisocyanate, chlorophenylene-2,4-diisocyanate,naphthylene-1,5-diisocyanate, diphenylene-4,4′-diisocyanate,4,4′-diisocyanate-3,3′-dimethyl-diphenyl,3-methyldiphenylmethane-4,4′-di-isocyanate and diphenyl etherdiisocyanate; and cycloaliphatic diisocyanates such as cyclohexane-2,4-and -2,3-diisocyanate, 1-methylcyclohexyl-2,4- and -2,6-diisocyanate andmixtures thereof and bis-(isocyanatocyclohexyl)methane andtriisocyanates such as 2,4,6-triisocyanatotoluene and2,4,4-tri-isocyanatodiphenylether.

[0042] Modified polyisocyanates containing isocyanurate, carbodiimide oruretonimine groups may be used. Blocked polyisocyanates,such as thereaction product of a phenol or an oxime and a polyisocyanate, may beused, having a deblocking temperature below the temperature applied whenusing a polyisocyanate composition. We have, however found that using acomposition according to the invention as a catalyst in the polyurethanereaction provides many benefits which have hitherto been achievable onlyby the use of such blocked polyiisocyanates and so the use of thesematerials may not be required.

[0043] The organic polyisocyanate useful with the organometalliccomposition of the invention may also be an isocyanate-ended prepolymermade by reacting an excess of a diisocyanate or higher functionalitypolyisocyanate with a polyol for example a polyether polyol or apolyester polyol. The use of prepolymers is common in commerciallyavailable polyurethane systems. Prepolymer systems may not requireaddition of a separate polyol to form the polyurethane bond. Polyols mayalready be incorporated in the isocyanate or prepolymer whilst furthercomponents such as chain extenders, polyols etc may be mixed with theisocyanate mixture before polymerisation.

[0044] Mixtures of isocyanates may be used in conjunction with theorganometallic composition of the invention, for example a mixture oftolulene diisocyanate isomers such as the commercially availablemixtures of 2,4- and 2,6-isomers. A mixture of di- and higherpolyisocyanates, such as trimers (isocyanurates) or pre-polymers, mayalso be used. Polyisocyanate mixtures may optionally containmonofunctional isocyanates such as p-ethyl phenylisocyanate.

[0045] Such-mixtures are well-known in the art and include the crudephosgenation products containing methylene bridged polyphenylpolyisocyanates, including diisocyanate, triisocyanate and higherpolyisocyanates together with any phosgenation by-products. Polymericmixtures of methylene bridged polyphenyl polyisocyanates containingdiisocyanate, triisocyanate and higher functionality polyisocyanates areoften referred to as polymeric MDI.

[0046] Preferably the polyisocyanate is liquid at room temperature.

[0047] The isocyanate-reactive compound is preferably a polyol suitablefor forming polyurethanes when reacted with an isocyanate compound inthe presence of a catalyst of the invention including those polyolsknown to the skilled person for the manufacture of polyurethanes andlike compounds. These include polymeric polyols such as polyetherpolyols, polyester polyols, polyolefin polyols, polycarbonate polyolsand polymer modified polyols.

[0048] Polyether polyols which may be used include products obtained bythe polymerization of a cyclic oxide, for example ethylene oxide,propylene oxide, butylene oxide or tetrahydrofuran in the presence,where necessary, of polyfunctional initiators. Polyether polyols havingaverage hydroxy functionalities from 2 to 8, number average molecularweights within the range of about 400 to about 30,000, and hydroxylnumbers within the range of about 560 to about 5 mgKOH/g are preferred.

[0049] Especially useful polyether polyols include polyoxypropylenediols and triols and poly(oxyethylene-oxypropylene) diols and triolsobtained by the simultaneous or sequential addition of ethylene andpropylene oxides to di- or trifunctional initiators as fully describedin the prior art Mixtures of the said diols and triols can beparticularly useful. Other particularly useful polyether polyols includepolytetramethylene glycols obtained by the polymerization oftetrahydrofuran.

[0050] Polyester polyols which may be used include hydroxyl-terminatedreaction products of polyhydric alcohols such ethylene glycol, propyleneglycol, diethylene glycol, 1,4-butanediol, neopentyl glycol,1,6-hexanediol, cyclohexane dimethanol, bis(hydroxyethyl)terephthalate,glycerol, trimethylolpropane, pentaerythritol or polyether polyols ormixtures of such polyhydric alcohols and polycarboxylic acids,especially dicarboxylic acids or their ester-forming derivatives, forexample succinic, glutaric and adipic acids or their dimethyl esters,sebacic acid, phthalic anhydride, tetrachlorophthalic anhydride,dimethyl terephthalate or mixtures thereof. Polyesteramides may beobtained by the inclusion of amino alcohols such as ethanolamine inpolyesterification mixtures. Polythioether polyols which may be usedinclude products obtained by condensing thiodiglycol either alone orwith other glycols, alkylene oxides, dicarboxylic acids, formaldehyde,amino-alcohols or aminocarboxylic acids.

[0051] Polycarbonate polyols which may be used include products obtainedby reacting diols such as 1,3-propanediol, 1,4-butanediol,1,6-hexanediol, diethylene glycol or tetraethylene glycol with diarylcarbonates, for example diphenyl carbonate, or with phosgene.

[0052] Polyacetal polyols which may be used include those prepared byreacting glycols such as diethylene glycol, triethylene glycol orhexanediol with formaldehyde or by polymerizing cyclic acetals.

[0053] Suitable polyolefin polyols include hydroxy-terminated butadienehomo- and copolymers and suitable polysiloxane polyols includepolydimethylsiloxane diols and triols.

[0054] Other polyols which may be used comprise dispersions or solutionsof addition or condensation polymers in polyols of the types describedabove. Such modified polyols, often referred to as “polymer” polyolshave been fully described in the prior art. Polyoxyalkylene polyolscontaining from 5 to 50% of dispersed polymer are particularly useful.Particle sizes of the dispersed polymer of less than 50 microns arepreferred. Polyol-terminated prepolymers may also be used.

[0055] Other useful isocyanate-reactive polymers include polymericpolyamines, especially diamines and triamines, corresponding to theabove-described polymeric polyols. Suitable polyamines of polyetherpolyols are those described, for example, in U.S. Pat. No. 3,654,374 orare obtained by the cyanoethylation of polyols followed byhydrogenation. Polyoxypropylene diamines and triamines and mixturesthereof are preferred. Also useful are polymers containing both aminoand hydroxyl groups obtained by the partial amination of polyols.Further isocyanate-reactive polymers include imino-functional polymers,such as polymers described in U.S. Pat. No. 4,794,129 together withmethods for their preparation and enamine functional polymers which maybe prepared either from secondary amine terminated resins (i.e.polyethers) by reaction with ketones/aldehydes having one or more alphahydrogens, or by reacting ketone/aldehyde terminated resins (bearingalpha hydrogens) with secondary amines, providing for removal of thewater formed in the reactions.

[0056] A composition containing a catalyst composition of the presentinvention and a polyisocyanate and compounds reactive therewith mayfurther comprise conventional additives such as chain modifiers,diluents, flame retardants, blowing agents, release agents, water,coupling agents, lignocellulosic preserving agents, fungicides, waxes,sizing agents, fillers, colourants, impact modifiers, surfactants,thixotropic agents, flame retardants, plasticisers, and other binders.The selection of these and other ingredients for inclusion in aformulation for a polyurethane composition is well known to the skilledperson and may be selected for the particular purpose.

[0057] The catalysts of the present invention are useful for themanufacture of polyurethane foams, flexible or rigid articles, coatings,adhesives, elastomers, sealants, thermoplastic polyurethanes, andbinders e.g. for oriented strand board manufacture. The catalysts of thepresent invention may also be useful in preparing polyurethaneprepolymers, i.e. urethane polymers of relatively low molecular weightwhich are supplied to end-users for curing into polyurethane articles orcompositions of higher molecular weight.

[0058] The catalysts are typically added to the isocyanate/alcoholmixture to give a concentration in the range 1×10⁴ to 10% by weight,preferably up to about 4% by weight based upon the weight of theisocyanate component.

[0059] Conventional release agents can be added to or used incombination with a polyisocyanate composition containing a catalystcomposition according to the present invention. Examples of conventionalrelease agents include polysiloxanes, saturated or unsaturated fattyacids (such as oleic acid) or fatty acid amides or fatty acid esters andpolyolefin waxes. However we have found that a further advantage of thecatalyst compositions of the present invention is that particularly whenthey are used in polyisocyanate resins for binding lignocellulosicmaterials for example, they function as exceptionally good internalrelease agents, so that a greatly reduced amount of a conventionalrelease agent is required. The reduction or elimination of therequirement for a release agent allows the process steps in making thepolyurethane articles to be reduced with the consequent savings inprocess time and improvement in process safety. Also external releaseagents are normally provided in a solvent so less solvent vapour isgiven off in the manufacturing process.

[0060] The organometallic composition of present invention can be usedin a process for preparing lignocellulosic bodies by binding alignocellulosic material with a polyisocyanate composition to form apolyurethane material by reaction with the hydroxy groups of thelignocellulosic material.

[0061] The methods used are well-known methods used in the art and aredescribed in WO-A-97117388 and other publications. More detaileddescriptions of methods of manufacturing wafer-board and similarproducts based on lignocellulosic material are available in the priorart.

[0062] The organometallic compositions of the invention are also usefulin many applications in which it is desired to effect curing ofisocyanate groups in a polyurethane. Such applications include coatings,e.g. decorative and industrial coatings for protection of wood, metals,plastics, glass, ceramics and other surfaces, including coatingssubjected to heat. Still further applications may be found incomposites, adhesives, elastomers, foams and thermoplastic polyurethanesfor use in automotive applications or footwear for example. Theapplications mentioned herein are intended only as examples since thepractical applications depend upon the type of polyurethane which isintended to be made.

[0063] The invention is illustrated but not limited by the followingexamples.

EXAMPLE 1

[0064] A composition according to the invention was made by mixingtogether tetra(n-butoxy) titanate (TNBT) with methyl ethyl ketone (MEK)in a mole ratio of 1:2.5.

[0065] The composition was used as a catalyst in an isocyanatecomposition used for the manufacture of oriented strand board (OSB). Thecomposition was added to the isocyanate resin at a rate of 3.5 wt %based on resin. The resin was used at a rate of 2.5 wt % based on wood.A 3-layer composite waferboard was manufactured on a test facilityfollowing normal methods used in the industry. The resin/woodcomposition was of the same composition for all layers but the watercontent of the core layer was 4% and that of the face layers was 8%.

[0066] A soap-wax release agent was used on the face of the plates usedto form the board. In conventional manufacture, it is necessary tore-apply this type of release agent each time a board is made. In theexample here, the release agent was applied only once at 25% of therecommended coverage and was not reapplied between subsequent boards.The release of the boards from the plates was monitored and theexperiment was concluded when a board required significant physicalforce to release it from the plate.

[0067] The control boards were made without using any using a catalystUsing the resin composition of the invention, the experiment was stoppedafter 12 boards were made without any sticking to the plates. When nocatalyst composition was used, the third board stuck to the plates andthe fourth was very difficult to remove so the experiment was stopped.This shows that the composition of the invention enables boards to bemade which release easily from the moulding plates even when no externalrelease agent is used.

[0068] The mechanical properties of the boards and of the control board(first from batch) is shown in the table. Example 1a, 1b and 1c are thefirst, 6^(th) and twelfth boards respectively of the consecutive batch.TABLE I Control Example 1a Example 1b Example 1c Modulus of 32.1 28.925.0 20.7 Rupture (Mpa) Modulus of 5700 5300 4800 4500 Elasticity (Mpa)Internal bond 0.387 0.282 0.160 0.080 (Mpa) Thickness swell 7.0 10.912.6 15.6 24 h (%) Water absorption 19.6 21.7 22.6 28.9 24 h (%)

EXAMPLE 2

[0069] A catalyst composition according to the invention was made bymixing together tetra(isopropoxy) titanate (TIPT) with MEK in a moleratio of 1:2.5.

[0070] The viscosity of a polyisocyanate composition containing thecatalyst composition (0.2% by weight) was tested by means of aBrookfield DV- II Programmable Viscometer (following the Operatinginstructions found in the Brookfield Operating Instructions Manual NoM/97-164-B299) at various intervals over a period of time during whichthe temperature was increased from 80° C. to 120° C. The results areshown in the graphs shown in FIG. 1. The results show that thecomposition is stable at 80° C. but when the temperature is increased to120° C. polymerisation of the isocyanate composition proceeds veryrapidly leading to a rapid increase in viscosity. The control samplecontained no catalyst.

EXAMPLE 3

[0071] A series of catalyst compositions according to the invention wasmade by mixing together a titanium compound with a coordinating compoundas identified in the Table 2. The mixing was done at room temperature(about 22° C.) under nitrogen for approximately 30 minutes (or until ahomogeneous mixture was obtained).

[0072] The catalyst compositions were mixed under an inert atmospherewith a commercial polyurethane prepolymer system sold under the DESMODURtradename by Bayer. The viscosity of each mixture was measured asdescribed in Example 2 at various temperatures. The results are shown inTable 3. The comparative compositions shown contained no coordinatingcompound. TABLE 2 Coordinating Catalyst Metal component component M:C(molar) A (comparison) TIPT — — B TIPT MEK 1:2.5 C (comparison) 2-Ethylhexyl titanate — — D 2-Ethyl hexyl titanate MEK 1:2.5 E (comparison)Ethyl titanate — — F Ethyl titanate MEK 1:2.5

EXAMPLE 4

[0073] Catalyst G was made by reacting together TIPT+ethyl acetoacetateat room temperature under nitrogen in the ratio 1 mole:2 mole andremoving by distillation 2 moles of isopropanol formed in the reaction.To the resulting orange semi-solid titanium complex, MEK is added andmixed under nitrogen at a ratio of 1 mol Ti:2.5 moles MEK to obtain ahomogeneous orange liquid.

[0074] Catalyst H was made by mixing together under nitrogen TIPT with2-dodecanone in the ratio 1 mole Ti:2.5 moles dodecanone.

[0075] Catalyst compositions G and H were used to cure a two-partcommercial polyurethane system comprising an isocyanate prepolymer and apolyether polyol with a chain extender and other additives. Thepolyurethane system was used according to the manufacturer'sinstructions and the catalyst was added to the polyol component. Thecompositions were allowed to cure at 25° C. and the viscosity wasmeasured at various times as before. A mercury catalyst (phenyl mercuricneodecanoate) was used as a comparison at an amount giving about 0.2 wt% of the Hg compound based on isocyanate.

[0076] The results are shown in Tables 4& 5. The results show that at aconcentration of 4.7×10⁻³ wt % of catalyst G and 0.084 wt % of catalystH, the cure time was similar to that provided by the mercury catalystbut that the viscosity profile is different in that the cream time ofthe composition containing the catalysts of the invention is longer,allowing for greater flexibility in handling the polyurethane system,e.g. by manipulating the composition in the mould to give a good surfacecoverage etc. The catalysts of the invention provide a very rapid cureonce the cure reaction begins. The environmental benefits of replacing amercury catalyst are also to be noted.

EXAMPLE 5

[0077] The shelf life of the compositions containing catalyst accordingto the invention was tested by adding 0.285 wt % a catalyst comprisingcatalyst B as a 25% solution in toluene to a polyol component (22g) of acommercial polyurethane system. The polyol was stored at 25° C. and 45°C. for several days and samples were tested at various times by mixingwith the polyisocyanate (10 g) of the polyurethane system and curingaccording to the manufacturer's instructions. The time for the mixedcomposition to achieve a viscosity (measured as before) of 40,000 cP isshown in Table 6. TABLE 6 Storage Reaction time (min.) to reach Days T(° C.) T (° C.) 40000 cP @ 25° C. 1 25 25 9 45 25 8 7 25 25 7.5 45 25 814 25 25 7 45 25 10 21 25 25 9.5 45 25 12 28 25 25 9

[0078] TABLE 4 Catalyst G 0.014 wt % 0.0077 wt % 0.0026 wt % Hg TimeViscosity Viscosity 0.0065 wt % 0.0047 wt % Viscosity 0.216 wt % (mins)(cP) (cP) Viscosity (cP) Viscosity (cP) (cP) Viscosity (cP) 0 1520 14401 2000 1640 1800 1640 1800 1480 2 2480 1840 1960 1720 1880 1600 3 38802160 2120 1840 1960 1800 4 13080 2800 2440 1960 2040 2080 5 40000 44802840 2160 2120 2480 6 11200 3440 2440 2240 3040 7 40000 4560 2840 24003880 8 6800 3480 2520 5200 9 12200 4480 2760 7200 10 27040 6360 296010200 11 40000 10200 3240 14960 12 19440 3600 22520 13 40000 3960 34880

[0079] TABLE 5 Catalyst H Hg 0.193 wt % 0.084 wt % 0.045 wt % 0.017 wt %0.216 wt % Time (mins) Viscosity (cP) Viscosity (cP) Viscosity (cP)Viscosity (cP) Viscosity (cP) 0 1540 1440 1540 1580 1440 1 1840 15201600 1720 1480 2 2320 1600 1680 1760 1600 3 4120 1680 1720 1800 1800 432480 1760 1760 1840 2080 5 40000 1880 1880 1880 2480 6 2040 1960 20003040 7 2280 2120 2080 3880 8 2640 2240 2200 5200 9 3200 2480 2320 720010 4120 2720 2480 10200 11 6080 3080 2640 14960 12 11560 3560 2840 2252013 40000 4280 3080 34880

[0080] TABLE 3 30° C. 50° C. 80° C. 100° C. 120° C. Prepolymer visc atvisc at visc at visc at visc at visc at visc at visc at visc at visc attime to reach system catalyst conc % 10 min 30 min 10 min 30 min 10 min30 min 10 min 30 min 10 min 30 min 55,000 cP Desmodur ™ A (comp) 3 11001750 8450 38100 35 min @ E744 100° C. B 1300 2900 1250 1550 400 650 265017450 50 min @ 100° C. Desmodur E743 C (comp) 2 700 5900 45 min @  80°C. C (comp) 3 1500 *55000 25 min @  80° C. D 3 2250 2450 850 850 300 350550 1250 1800 7500 40 min @ 120° C. Desmodur E28 E (comp) 3  1 min @ 25° C. E(comp) 2  1 min @  25° C. F 3 2500 3750 3850 >55,000 15 min @ 80° C.

1. A catalyst composition suitable for use to catalyse the reaction ofan isocyanate compound or prepolymer thereof with an alcohol, polyol orprepolymer thereof to form a polyurethane comprising a mixture of (a)anorganometallic compound selected from (i) an alkoxide compound offormula M(OR)_(x), where M is titanium, zirconium, hafnium aluminium,cobalt or iron or a mixture of these metals, where x is the valency ofthe metal, and OR is the residue of an alcohol ROH in which R comprisesan (optionally substituted) C₁₋₃₀ cyclic, branched or linear, alkyl,alkenyl, aryl or alkyl-aryl group or a mixture thereof, or (ii) acomplex of titanium, zirconium and/or hafnium and an acetoacetate esterand (b) a coordinating compound selected from a ketone, aldehyde,carboxylic acid, sulphonic acid, nitrile or an imine, wherein saidcoordinating compound does not comprise a diketone or an acetoacetateester.
 2. A catalyst composition as claimed in claim 1 wherein the metalis titanium or zirconium.
 3. A catalyst composition as claimed in claim1 or claim 2 wherein said coordinating compound is a ketone.
 4. Acatalyst composition as claimed in any of the preceding claims whereinthe molar ratio of organometallic compound to coordinating compound isin the range 1:0.5 to 1:10.
 5. A catalyst composition as claimed inclaim 4 wherein, when the metal is titanium, the molar ratio is in therange 1:0.5 to 1:4 and when the metal is hafnium or zirconium, the molarratio is in the range 1:4 to 1:10.
 6. A curable composition for themanufacture of a polyurethane material said composition comprising: A. apolyol component and B. a polyisocyanate component and C. a catalystcomposition comprising a mixture of: (a)an organometallic compoundselected from (i) an alkoxide compound of formula M(OR)_(x), where M istitanium, zirconium, hafnium aluminium, cobalt or iron or a mixture ofthese metals, where x is the valency of the metal, and OR is the residueof an alcohol ROH in which R comprises an (optionally substituted) C₁₋₃₀cyclic, branched or linear, alkyl, alkenyl, aryl or alkyl-aryl group ora mixture thereof, or (ii) a complex of titanium, zirconium and/orhafnium and an acetoacetate ester and (b) a coordinating compoundselected from a ketone, aldehyde, carboxylic acid, sulphonic acid,nitrile or an imine, wherein said coordinating compound does notcomprise a diketone or an acetoacetate ester.
 7. A composition asclaimed in claim 6 wherein the catalyst is added to either the polyolcomponent or the isocyanate component.
 8. A process for the manufactureof a polyurethane composition, comprising the step of mixing together apolyol component and a polyisocyanate component and a catalystcomposition, said catalyst composition comprising a mixture of: (a)anorganometallic compound selected from (i) an alkoxide compound offormula M(OR)_(x), where M is titanium, zirconium, hafnium aluminium,cobalt or iron or a mixture of these metals, where x is the valency ofthe metal, and OR is the residue of an alcohol ROH in which R comprisesan (optionally substituted) C₁₋₃₀ cyclic, branched or linear, alkyl,alkenyl, aryl or alkyl-aryl group or a mixture thereof, or (ii) acomplex of titanium, zirconium and/or hafnium and an acetoacetate esterand (b) a coordinating compound selected from a ketone, aldehyde,carboxylic acid, sulphonic acid, nitrile or an imine, wherein saidcoordinating compound does not comprise a diketone or an acetoacetateester.
 9. A process as claimed in claim 8 wherein the catalystcomposition is mixed together with one of the polyol or thepolyisocyanate components before the polyol and polyisocyanatecomponents are mixed together.
 10. A process as claimed in claim 8,wherein the catalyst component is added to a mixture of the polyol andpolyisocyanate components.
 11. A process as claimed in any of claims8-10 further comprising the step of heating the mixture of polyolcomponent and polyisocyanate component.
 12. A polyol compositioncontaining a catalyst composition as claimed in any of claims 1-5.
 13. Apolyisocyanate composition containing a catalyst composition as claimedin any of claims 1-5.